1. Field of the Invention
This invention relates to a connector which is used for connecting electrically between electronic devices installed in a vehicle, and is adjusted an impedance thereof with an electrical wire and a mating connector. This invention also relates to a method of manufacturing the connector.
2. Description of the Related Art
Various electronic devices are installed in a car as the vehicle. Therefore, in the car, a wiring harness is wired for transmitting electric power and signals. The wiring harness has a plurality of electrical wires and connectors.
The electrical wire has a conductive core wire, and a cover made of insulating synthetic resin for covering the core wire, and is called generally a covered (electrical) wire. The connector has a terminal made of electrical conductive metal, and a connector housing for receiving the terminal. The connector housing is made of insulating synthetic resin, and fits to a mating connector of the electronic device for transmitting required power supply and signals to the electronic devices.
Impedance of the connector or the mating connector of the electronic device can be adjusted to match with the fitted connector or an electrical wire joined with the terminal. When a large amount of signal is transmitted at high speed, the impedance requires adjustment.
A connector for connecting a main body of a navigation system, for example, a GPS (Global Positioning System) for calculating a present position and a display device for indicating the present position and a target position as electronic devices is required to transmit a large amount of the signal at high speed, because the display device is required to have a higher resolution and to show the present position at real time. Impedance matching becomes more necessary.
Thereby, the amount of signal transmitted from the main body to the display device is increased, and the signals are required to be transmitted at higher speed so as to show the transmitted signals at real time in the display device. There are an imbalance type (single-end type) and a parallel type (differential type) as general transmitting types.
The single-end type is to detect differences of voltages between one signal line and ground line for detecting a high state and a low state of digital signal, and is used generally.
The differential type uses two signal lines (positive and negative lines), and detects the high state and the low state by detecting the differences of voltages between the two signal lines. One of two signals transmitted through the two signal lines has a negative voltage in case, but the one signal is called a positive signal in this specification. The other of two signals transmitted through the two signal lines has a positive voltage in case, but the other signal is called a negative signal in this specification.
The two signals of the differential type transmission have the same voltage level with different phase angles shifted 180 degrees to each other. According to the differential type, noise generated in the two signal lines is canceled at inputting the signals into a receiver. Thereby, the differential type transmission can transmit signals faster than the single-end type transmission.
This applicant proposed a connector having a terminal for positive signals, a terminal for negative signals, and a ground terminal for high-speed differential type transmission, for example patent reference 1. A connector described in a patent reference 1 is joined at an end of a cable.
The cable has an electrical wire for positive signals, an electrical wire for negative signals, and an electrical wire for grounding. The electrical wire for positive signals is joined with the terminal for positive signals. The electrical wire for negative signals is joined with the terminal for negative signals. The electrical wire for grounding is joined with the terminal for grounding. In the cable, the electrical wire for positive signals, the electrical wire for negative signals, and the electrical wire for grounding are positioned in parallel. The electrical wire for positive signals, the electrical wire for negative signals, and the electrical wire for grounding are positioned to form triangularly in a section of the cable.
In the connector according to the patent reference 1, the terminal for positive signals, the terminal for negative signals, and the terminal for the ground are located triangularly similarly as locations of the wires in the cable. Thereby, the connector according to the patent reference 1 has a constant relationship of relative positions of transmission paths of each signal through the cable to the connector. Thus, impedance matching between each of the electrical wires in the cable is adjusted. The patent reference 1 is Japan Patent Application Laid open 2003-100399.